Variable speed mechanism



' D. W. STROM VARIABLE SPEED MEGHANISM Nov; 1s, 1941.

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Nov. l8, 1941. D. w. sTRoM v VARIABLE SPEED M'ECEANISE 2 vSmeets-sheet 2 Filed Aug. 30, 1939 a. 7 2 M M n M w,

uw WFM`X UV 3 Patented Nev. 18, 1941 e l j A2,262,782

' UNITE-o STATES.' 4PATIsN'I oFF-lcs Pazafatas I l David W. Strom, Elmira. N. Y., assigner to Hardinge Brothers, Inc., Elmira, N. Y.

Appueeuen samt so, 193s, serien No. 292,681' 1s calms. (ci. u-zsoj'n This invention relates to `improvements .in

mechanisms'for producing variable speeds, and more particularly/to mechanisms of this kind of thebelt driven type.

There are on the market manyl types of variable speed mechanisms which are quite satisfactory when operated at relatively slow speeds. When these mechanisms are operated at high speeds, as required for driving many modern machines, these mechanisms become noisy, vibrate excessively and wear at their belts rapidly. Vibration is particularly objecat the present time lt is not intended to limit this invention `,to a

speed change mechanism having two adjustable pulleys, since considerable variation in speed may uensble when the mechanism is to be used 1nv connection with a precision machine or implement, such as a lathe, in which the vibrations produce irregularities in the cut and thus produce defective work.

One of the objects of this invention ls to pro-4 be obtained by means of a single. adjustable pulley.

In the particular embodiment of the invention shown by way of illustration in the accompany-v ing drawings, A, Fig. 2, represents a base on which the variable speed mechanism may be mounted. This base may be a table or shelf upon orbelow which the variable speed mechanism is mounted, or the base.l may be in the form oi' an upright orinclined support for the mechanism. A plurality of columns or posts I extend outwardly from the base for supporting the mechanism in spaced relation thereto. This mechanism includes a' frame membery of any suitable construction, that shown comprising two equal parts 8 and 9, each of which forms a complete, side of thefframe member vand portions of the two ends thereof. The sides lof the frame Another object of'this invention is to provide a variable speed mechanism of this kind, in which a belt operates in coniunction with a pair of pulleys each comprising a pair of cones, one of which is adiustable relatively to the `other, the two cones of a pulley being rotatably mounted independently of each other. l

Another object is to provide a change 'speed mechanism of this kindwith means of improved base in any suitable manner.

member are preferably of"channel-shaped cross section.'` The two parts of the frame member may ,besecured togethervin any suitable manner, `for example,'by.means of bolts or screws II arrangedin the end portions of the frame member i vTh ,'framem'ember may mounted on the lar construction shown by way of example, bolts I0 extend through suitable apertures in the channel-shaped side portions of the frame memconstruction for quickly removing a. driving connection between the two cones of a pulley so that a belt may be removed by passing the same between the cones.

Other objects of this invention will appear from the following description and claims.

In the accompanying drawings:

Fig. -1 is a sectional plan view of a speed change mechanism embodying this invention.

Fig. 2 is a sectional side elevation thereof, the

section being taken approximately on linev 2-2,

Fig. l, on a reduced scale.

Fig. 3 is a. fragmentary sectional plan vview thereof showing the parts in the position in which the two' cones of a pulley are disconnected.

bers and through the posts l and are secured to the 'base A. A resilient or cushion mounting In the particumay also be provided, if desired, and for this. purpose, rubber washers I2 may be provided.

about the bolts I0 at opposite faces of the frame Y member. Smaller washers or sleeves I3 may be provided Within the apertures or bolt. holes iny the frame member to keep the bolts out of metalliccontact with the frame member. A spacing sleeve I3a is shown for holding the washers or sleeves I3 in place. Any other form of mount- In order to provide a large variation in speed,

I have shown in the accompanying drawings al y mechanism employing two pulleys embodying my ing for the frame member may be provided, if desired. f

The four sides of the frame member form a.

Y substantially hollow rectangle with a relatively are of approximately channel-shape,being prvided with an outer peripheral wall I4 having integral flanges I5 and IB. The frame member shown is desirable, since it is made of two equal parts, both of which can be cast fromv invention. It will be understood, however, that the same pattern, and the parts can be easily conical.

assembled and separated. -A frame member of any other suitable or desired construction may, however, be employed if desired.

The frame member forms a support for the' bearings of the shafts of the change speed mechanism. Each pulley includes two cone disks, and

each cone disk is mounted on its own shaft.` The shafts 20 and 2| each have a cone disk rigidly mounted thereon, and these shafts transmitpower into and out of the change speed mechanism. Either shaft may be connected with the driving from the change speed mechanism. 20, in the construction shown, is provided with a relatively small pulley 22 cooperating with a belt 23, and the other shaft 2| is provided with a larger pulley 24 cooperating with a belt l25. If-

Y shown) is preferably provided with a larger. pulley connected by the belt 23 to the smaller pulley 22. 'Any other means may, of course, be provided for transmitting power to and from the shafts 20 and 2|.

Each pulley or sheave ofv the change speed mechanism includes a pair of disks 21 and '28, each of which has a convex surface which may be of substantially frustoeconical shape. vThese convex surfaces of the two' disks of a pulley face each other to form a pulley capable of cooperating with a belt 26 of a modified V type whose opposite, bevelled or inclined edges engage with the convex faces of the disks to form a driving connection with the pulleys. Preferably, the convex faces of the disks are slightly curved or bowed outwardly, so that the disks are not truly frusto- 'I'he advantage of this constructionwill be hereinafter pointed out. If the disks are made so as to be accurately in balance, vibrationsdue to unbalanced conditions of the disks are avoided. The balancing of the disks may be effected in any suitable or well known manner, no balancing means being shown. For convenience, these disks will be herein referred to as cone disks, and the driving faces thereof are referred to as convex, regardless of whether they are frusta-conical or curved in cross section. Since the two pulleys and their bearing mountings are identical, only one of them will be specifically described'.

'I'he cone disk 21 of one'pulley is rigidly connected to the shaft 20 and the corresponding disk of the other pulley is secured to the shaft 2|. The other cone disk 28 of each pulley is rotatably mounted and adjustable toward and from the cone disk 21 to vary the effective diameter of the pulley formed by the two disks. In the particular construction shown, the cone disk 28 is rotatably mounted on an adjustable and normally non-rotating shaft or rod 29, for example, by

means of a suitable ball bearing 30, which is so formed that the disk 28 is free to rotate about the adjustable shaft 29 but is held against end wise movement relatively to the same. For this purpose, the inner race ring or sleeve of the ball bearing is secured to the end of the shaft or rod 29 and the outer race ring or sleeve is secured to the cone disk 28,'for example, by means of an motor while the other shaft delivers the powerI The shaft cured, is suitably journalled on the frame of the mechanism. In the constructionshown, a pair of ball bearings 32 is provided for this'purpose, l

which arev spaced apart by means of a pair of concentric` sleeves 33 and 34. The inner race rings of the bearings 32 and the sleeve 33. are suitably secured to the shaft 20, and the outer race rings of the ball bearings and the outer sleeve 34 are suitably secured to a hub or cylindrical boss '35, preferably formed integrally with the frame of the mechanism. 'I'he inner ends of the shafts 20 and 2| are preferably provided with outwardly extending anges 36 to which the cone 21 may be suitably secured in any suitable manner, for example, by means'of rivets, as shown. Any-other means for journalling. the shafts 20 and 2| and for securing the conedisks .21 thereto may be employed.

The adjustable shaft29 may be adjusted lin any suitable manner, that shown being normally non-rotating and being moved. axially relatively I 1 arid 3. This construction has the ladvantage that as the repeated adjustment of the shafts 29 relatively to the internally threaded sleeves 40 and 4| produces wear on the threads, 'resulting in looseness of the shaft 29, one or both of the sleeves 40 and 4| may be turned to a slight exl tent upon releasing the corresponding set screw 44, to take up the wear in the screw threads. In this manner, vibrations due to looseness of the shafts 29 may be avoided.

From the foregoing description, it`wi11 be ob-l .Ivious thatV the effective diameter of a pulley formed by the cone disks 21 and 28 may readily be varied by turning the adjusting shafts 29 so as to move the cone disk 28 toward and from the other disk 21. Whentwo pulleys are employed,

' the cone disk 28 of one pulley is moved toward its cooperating disks 21 while the disk 28 of the other pulley is moved away from its cooperating disk 21. In this manner, the effectivev or driving diameter of one pulley is increased while that of the other pulley is decreased. In this manner, the belt tension is maintained approximately uniform. However, by making the frus to-conical faces of the two disks slightly curved annular sleeve 3| secured by screws or other I as described, the belt may be maintained at uniform tension throughout all adjustments of the disks relatively to each other, thus eliminating the need for an idler.

, Means are preferably also provided for simultaneously moving the cone disks 28 of the two pulleys relatively to their cooperating disks 21. For this purpose, the two adjusting shafts 29 o f the two pulleys are connected with each other in any suitablemanner for simultaneous rotation. For example, each shaft 29 may have a sprocket wheel 48 rigidly secured thereon, each of these sprocket wheels cooperating with a sprocket chain 49. One of the chains 49 also cooperates with another` sprocket wheel 50 mounted on one end of a countershaft 5| and the other sprocket chain 49 cooperates 'with another sprocket wheel 52 mounted on the other end of the countershaft 5|.

This shaft may be rotatably mounted on the frame of the mechanism in any suitable or desired manner, for example, by means of a pair of upl y wardly extending posts 54, thel lower ends of which are secured to the frame of the mechanism, and the other ends of which rotatably support the'sprocket shaft. 6|. One ofthe threaded shafts29 is preferably also provided with a hand `wheel 55 for turning the shaft 29. Any rotation of thehand wheel 55 is transmitted directly to the shaft 29 to which it isconnected and also through the sprocket chains 49 and shaft 5| .to the other threaded shaft 29. The construction shown also results in the moving of one cone disk 28 toward its cooperating disk 21,'while the other l of the hand wheel and sprocket gearing described. l

the countershartl is provided'with a threaded portion 51 which cooperates with a correspondingly internally-threaded part 68 at the upper end of one of the posts 54. If the pitch or the thread on the portion 51 is similar to the pitch of the threaded portions ofthe shafts 29, then the shaft 5I will move transversely of the mechanism to the same extent as the shafts' 29. Consequently,

' the sprocket wheels 48 will always remain in proper alinement with the sprocket wheels 59 and 52 onthe shaft 5l.v

It will be noted that as thus far described, each cone disk of a pulleyv may turn independently of the other. Preferably, however, I provide means whereby both cone ,disks of the pulley may be connected with each other to prevent -relative rotary `motion of the cone disks of a pulley. For.v

this purpose, the shafts 28 and 2l are made hollow, being provided throughout the greater portions of the length thereof with a relatively lsmall bore adapted to receive a stem 68 of a connecting member. The inner ends of the shafts and 2l have a bore of larger diameter, indicated at 6I. The shafts 29 are each provided with a bore or recess 62, which extends inwardly from the inner v end thereof, this bore being substantially similar in dimensions to the bore 6I of the shafts 20 and 2|. The inner end of the connecting member is provided with a non-circular connection portion or head 63, which has a driving connection with both of the cones of a pulley when in the position shown in Fig. l', but which may be withdrawn into the bore or recess .6 i as shown in Fig. 3. The stem 60 of each connecting member may be held in any desired position, for example, by means of a set screw 65. The connecting portion or head 63 may establish a driving connection between the two disks 21 and 28 in any suitable or desired manner. `In the particular construction illustrated, the'head 63 is of hexagonal'y cross section and cooperates with hexagonal portions of the cone disks which it. connects. Preferably, I provide on each cone disk, a smaller disk 61 having a hub portion winch is of the same cross sectional shape as the head of the connect- A ing member 63, these disks 61 being provided with hexagonal apertures in the construction illustrated, in which the head of the connecting member may engage. The disks 61 may be secured to the cone disks in any suitable manner, for example, by means of rivets, the same rivets being employed for holding the disk 61 on t-he cone disk 21 as are used for holding this disk on the flange parts may bevomitted if desired, since they are mainly needed when the mechanism iscalled upon to transmit considerable power.

'I'he construction described results in a change Speed whichmy be Operated at 111811 I speeds without any objectionable vibration. This isdue to a large extent to the fact that the two cone disks of each pulley are mounted on separate shafts or bearings. The two separately mounted disks can be more easilywmounted on the frame of the mechanism to operate quietly and `without vibration than would be possible if the two disks were mounted onthe same shaft with one of them adjustable lengthwise thereof, which would necessitate a certain amount of looseness l of the adjustable cone disk on the shaft in order to make the adjustment possible. This freedom from vibration not only is necessary in driving" precision machines, but also greatly increases the life of the belt.

By mounting the bearings for the cone disks 28,

on the adjustable shafts so that each bearing is moved with its cone disk 28, the cone disk remains in correct adjustment and relation to its bearingl during all movements of the adjustable disk relatively to its cooperating disk. Conse- 'quently, by means of this arrangement, vibration of the mechanism can be prevented even when the same operates athigh speeds.

Another advantage resulting from the independent mounting of thetwo cone disks on separate shafts and in the removable driving connection between the two cone disks is that by means of this construction, the belt can be easily removed from the disks and replaced by another beit. vIn order to do this, both of the disks 2lA can be separated from their cooperating disks 21. In order to permit this to be done, the sprocket.

wheels 58 and 52 may be detachably secured on the sprocket shaft 6I vin any suitable manner,

rfor example. by means of set screws 69, su that the two cone disks 28 may be moved independently of each other, or the chains 49 may be provided.with removable pins 10, so that oneor both of these chains may be removed from their sprocket Wheels. When the disks of both pulleys are separated, the belt 29 will, of course, be loose, so that a portion thereof can easily be turned through approximately a right angle to permit it to pass-between the separated disks of the pulley, this being done when the connecting member '63 is in the position shown in Fig. 3.

The construction described has the further advantage that the tension of the belt 26 can be readily adjusted, for example, for compensating' which shows the position of the adjusting Wheel 55. When a device of this type is used, the movement of one adjustable disk 28 without a corresponding adjustment of the other disk 28 will change the ratio so that the gauge will not be correct. This, however, 'may beavoided by means of the construction shown, when adjusting the tension of the belt 26, by moving each of `the adjustable disks 28 toward its cooperating disk 21 substantially to the same extent. After making such adjustment, the chain 49, whichhas at. 'rm connecting member n and associated been removed, is` replaced, whereupon vthe slack in the belt is taken up without a substantial variation in the speed ratio of the mechanism.

The forming of the frame of the mechanism in two separate partsextending lengthwise of the mechanism has a further advantage that the various .parts of the mechanism can be readily assembled or taken part when the twofframe able shaft having one of saiddisks rigidly secured to an end thereof, a bearing for the other disk which provides rotation of said other disk in dependently of said shaft and in spaced relation thereto, and means for moving one of said disks toward and from the other disk.

2. 'A sheave comprising a pair of disks having convex surfaces facing each other and spaced to receive a flexible belt between them, a rotatable shaft to which one of said disks is secured and which terminates at said disk, a relatively sta- .tionary support on. which the other disk is mounted to rotate independently of said first disk, means for adjusting said stationary support to move said other disk toward and from said first disk, and a removable driving connection between said disks which may be removed Without moving said shaftv and which, when removed, permits removal and replacing of a belt.

3. A sheave comprising a pair of disks having convex surfaces facing each other and spaced to receive a belt between them, a rotary shaft having one of said` disks mounted for rotation therewith, said other disk being spaced from said first disk and from said shaft, a bearingfor said other disk. and adjusting means for moving said other disk and its bearing toward and from said rst disk,and for moving said other disk from said rst disk and said shaft to an extent suicient to permit said belt to be passed between said disks.

4. A sheave comprising a pair of disks having convex surfaces facing each other and spaced to receive a belt between them, a rotatable shaft on which one of said disks is secured, a bearingfor the otherdisk which is mounted independently of said shaft 'd permits rotation of said other disk relativelytov vsaid first disk, 'means for adjusting said other'disk and its bearing toward and from said rst disk, and means movable independently of said shaft and said disks into and out of position for releasably connecting said disks to cause the same to'rotate in unison.

5. 'A sheave comprising a pair of disks having convex surfaces facing each otherand spaced to receive a belt between them, a hollow rotatable shaft to which one of said disks is rigidlysecured, an adjustable support on which the other disk is mounted to rotateA independently of said flrst disk and which is adjustable to move said other disk toward and from said first disk, and

shaft to which one of said'disks is secured, an

a connecting device arranged in said hollow shaft and movable out of said hollow shaft into driving engagement with said other disk to cause said disks t0 rotate in unison.

Vafaea'zsa 6. A sheave comprising a pairof disks having convex surfaces facing each other and spaced to receive a belt between them. ahollow rotatable adjustable support on which the other disk is mounted to rotate independentlyV of said' first disk and which is adjustable to'move said other disk toward and from said first disk,l a connecting device arranged in said holiowshaft and movable out of said hollow shaft into driving engagement with said other disk to cause said disks to rotate in unison, said connecting device having ay part extending beyond the outer end of said hollow shaft for moving said connecting member into and out of said hollow shaft for connecting said disks, and means on said shaft for securing said connecting member in adjusted position.

l 7. A sheave comprising a pair of disks having convex surfaces facing each other and spaced to receive a exible belt between them, a rotary shaft on which one of said disks is mounted, a second shaft having a bearing on the outer portion thereof and on which said other disk is mounted to rotate about said second shaft independentlyofsaid other disks, said second shaft having a threaded portion whereby rotation of said second shaft adjusts said other disk toward and from said rst disk, and means for releasably connecting said disks to cause the same to rotate in unison.

8. A variable speed mechanism including a frame, a belt, a pair of sheaves mounted on said frame and each comprising a pair of disks hav-I ing convex surfaces facing each other and spaced to receive said belt between them, a driving shaft journalled in said frame and having the disk of one sheave secured thereon, a driven shaft also journalled in said frame and having a disk of the other sheave secured thereto, a pair of adjustable members mounted on said frame and movable toward and from said shafts in the direction of the axes thereof, said other disks of 'said sheaves being journalled on said adjustable members to rotate independently of each other and being adjustable toward and from said rst mentioned disks, and means operable at will independently of said disks and said shafts for connecting the disks of a sheave to cause said disks to rotate in unison, said belt being removable from said sheaves `by passing the same between said disks when said disks are separated and when said connecting means are moved into a non-connecting position.

9. A variable speed mechanism, including a frame, a belt, a pair of sheaves mounted on said frame and each comprising a pair of disks having convex surfaces facing each other and spaced to receive said belt between them, a driving shaft journalled in said frame and havingthe disk of one sheave secured to an end portion thereof, a driven shaft also journalled in said frame and having a disk of the other sheave secured to an end portion thereof, a pair of adjustable meinbers mounted on said frame and movable toward and from said shafts in the direction of the axes thereof,v said other disks of said sheaves being journalled on said adjustable members to rotate independently of each other and being movable with said members toward and from said `irst mentioned disks and toward and from said shafts, means operable at will independently of said shafts for connecting the disks of a sheave to cause said disks to rotate in unison, said belt being removable from said sheaves by passing the same between said disks when said disks are each other and spaced to receive said belt beseparated and when said connecting means are moved into a non-connecting position. and means for simultaneously operating both of said ad- Justable members.

10. A pair of sheaves each comprising a pair of disks having convex surfaces facing each other and spaced to receive a belt between them, each of said disks being journalled to rotate independently of the other, a power transmitting shaft rigidly secured to a disk of one sheave, another power transmitting shaft rigidly secured to a disk of the other sheave, means operatively connected with the other disks of said sheaves for adjusting the sametoward and from said first mentioned disks and for spacing said i'lrst mentioned disks from said other disks for permitting the belt to be passed between the disks, and releasable means associated with each sheave and movable independently of said shafts into and out of driving connection with both of said i disks to cause the same to rotate in unison.

11. A sheave comprising a pair of disks having convex surfaces facing each other and spaced to receive a belt between them, each'of said disks being journalled to rotate independentlyof the other, means operatively connected with a diskl for adjusting the same toward and from the other disk and for spacing said first mentioned disk from said other disk for permitting the belt to be between them, a power shaft secured to one of said disks, the axial portions of said disks being provided with non-circular apertures, and a connecting member which is movable independently of said shaft into a position to extend into the apertures of said disks and to Cil tween them, a rotatable shaft for each sheave, one disk of each sheave being secured to one of said shafts, said shafts being held against axial movement, threaded shafts on which the other of said disks are journalled, each to rotate independently of its cooperating disk, said threaded shafts engaging stationary threaded parts of said frame and being adjustable toward and from said first. mentioned disk to move said adjustable disks relatively to said iirst disks, gearing connecting said threaded shafts for simultaneously moving one of said adjustable disks toward its cooperating disk while the other adjustable disk is moved away from its cooperating disk, and'means for disconnecting said gearing other of said disks are journalled, each to rotate.

engage in said non-circular apertures to form a drivingV connection between said disks and which may-be withdrawn from one of said disks to provide an open space between said disks through which a belt may be passed.

12. A variable speed mechanism including a frame, a belt, a pair of sheaves each comprising a pair of disks having convex surfaces facing each other and spaced to receive said belt between them, a rotatable shaft for each sheave on which one disk of a sheave issecured, threaded shafts which are normally stationary and on which said other disks of said sheaves are mounted to rotate independently of their cooperating disks and which have a engagement with a fixed part of said frame, whereby the turning of said threaded shafts moves the same axially to adjust said other disks relatively to said nrst disks, a countershaft mounted on said frame and having a threaded englsement therewith of similar pitch to the threads of said other shafts, and gearing connecting said other shafts and said coimtershaft, whereby' said 'other shafts and countershaft advance axially in the same direction during adjustment of said other disks.

13. A variable speed mechanism including a frame,abelt',apairofsheaveaeheomprising to permit an adjustablefdisk to be moved relatively to its cooperating disk independently of the other adjustable disk.

14. A variable speed mechanism including a frame, a belt, a pair of sheaves each comprising a pair of disks having convex surfaces facing each other and spaced to receive said belt between them, a rotatable shaft for each sheave, one disk of each sheave being secured to one of said shafts, said shafts being held against axial movement, threaded shafts on which the independently of its cooperating disk, said threaded shafts engaging stationary threaded parts of said frame and being adjustable toward andfrom said flrst mentioned disk,l to move said adjustable disks relatively to said flrst disks, gearing including a sprocket chain for connecting said threaded shafts for simultaneously moving the adjustable disk of one sheave toward its cooperating disk while the adjustable disk of the other sheave is moved away from its cooperating disk, said sprocket chain being detachable from said gearing to permit said adjustable disks to be moved independently of each other relatively to their cooperating disks.

l5. A variable speed mechanism of the type including a pair of sheaves connected by a belt and in which each sheave is formed of a-pair of disks having convex surfaces facing each other, said mechanism including a frame comprising two substantially similar longitudinally extending parts releasably secured together, each frame part having one disk of each sheave mounted thereon to rotate about axes extending transversely thereof with the convex surfaces extending toward the same side thereof, said frame parts when vsecured together presenting the disks on one frame part in operative lrelation to and in axial alinement with the disks of the other .frame part.

18. A variable speed mechanism according to claim 15 and provided with means operable at will for forming a driving. connection between the disksofasheavetocausethedisksofthesheave -tomttelnunilolh apairofdiskshavingeonvsxsurfacesfaeing.

DAVID W. BTROM.. 

